1 files changed, 1 insertions, 1 deletions
diff --git a/boxes.hh b/boxes.hh
index c9ff3e62ef..5d0be85452 100644
--- a/boxes.hh
+++ b/boxes.hh
@@ -49,7 +49,7 @@ struct Interval {
 	if (h.max>max)
 	    max = h.max;
     }
-    
+    Real length() const;
     void set_empty() ;
     bool empty() { return min > max; }
     Interval() {